Rollup merge of #97415 - cjgillot:is-late-bound-solo, r=estebank

Compute `is_late_bound_map` query separately from lifetime resolution

This query is actually very simple, and is only useful for functions and method.  It can be computed directly by fetching the HIR, with no need to embed it within the lifetime resolution visitor.

Based on #96296

Author: Dylan-DPC

compiler/rustc_ast_lowering/src/lib.rs

@@ -672,9 +672,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             LifetimeRes::Param { .. } => {
                 (hir::ParamName::Plain(ident), hir::LifetimeParamKind::Explicit)
             }
-            LifetimeRes::Fresh { param, .. } => {
-                (hir::ParamName::Fresh(param), hir::LifetimeParamKind::Elided)
-            }
+            LifetimeRes::Fresh { .. } => (hir::ParamName::Fresh, hir::LifetimeParamKind::Elided),
             LifetimeRes::Static | LifetimeRes::Error => return None,
             res => panic!(
                 "Unexpected lifetime resolution {:?} for {:?} at {:?}",
@@ -1576,10 +1574,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     (hir::ParamName::Plain(ident), LifetimeRes::Param { param, binder: fn_node_id })
                 }
                 // Input lifetime like `'1`:
-                LifetimeRes::Fresh { param, .. } => (
-                    hir::ParamName::Fresh(outer_def_id),
-                    LifetimeRes::Fresh { param, binder: fn_node_id },
-                ),
+                LifetimeRes::Fresh { param, .. } => {
+                    (hir::ParamName::Fresh, LifetimeRes::Fresh { param, binder: fn_node_id })
+                }
                 LifetimeRes::Static | LifetimeRes::Error => continue,
                 res => {
                     panic!("Unexpected lifetime resolution {:?} for {:?} at {:?}", res, ident, span)
@@ -1749,18 +1746,18 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     ) -> hir::Lifetime {
         debug!(?self.captured_lifetimes);
         let name = match res {
-            LifetimeRes::Param { param, binder } => {
+            LifetimeRes::Param { mut param, binder } => {
                 debug_assert_ne!(ident.name, kw::UnderscoreLifetime);
                 let p_name = ParamName::Plain(ident);
                 if let Some(LifetimeCaptureContext { parent_def_id, captures, binders_to_ignore }) =
                     &mut self.captured_lifetimes
                     && !binders_to_ignore.contains(&binder)
                 {
                     match captures.entry(param) {
-                        Entry::Occupied(_) => {}
+                        Entry::Occupied(o) => param = self.resolver.local_def_id(o.get().1),
                         Entry::Vacant(v) => {
                             let p_id = self.resolver.next_node_id();
-                            self.resolver.create_def(
+                            let p_def_id = self.resolver.create_def(
                                 *parent_def_id,
                                 p_id,
                                 DefPathData::LifetimeNs(p_name.ident().name),
@@ -1769,10 +1766,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             );
 
                             v.insert((span, p_id, p_name, res));
+                            param = p_def_id;
                         }
                     }
                 }
-                hir::LifetimeName::Param(p_name)
+                hir::LifetimeName::Param(param, p_name)
             }
             LifetimeRes::Fresh { mut param, binder } => {
                 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
@@ -1792,21 +1790,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                 span.with_parent(None),
                             );
 
-                            let p_name = ParamName::Fresh(param);
-                            v.insert((span, p_id, p_name, res));
+                            v.insert((span, p_id, ParamName::Fresh, res));
                             param = p_def_id;
                         }
                     }
                 }
-                let p_name = ParamName::Fresh(param);
-                hir::LifetimeName::Param(p_name)
+                hir::LifetimeName::Param(param, ParamName::Fresh)
             }
             LifetimeRes::Anonymous { binder, elided } => {
-                let l_name = if elided {
-                    hir::LifetimeName::Implicit
-                } else {
-                    hir::LifetimeName::Underscore
-                };
                 if let Some(LifetimeCaptureContext { parent_def_id, captures, binders_to_ignore }) =
                     &mut self.captured_lifetimes
                     && !binders_to_ignore.contains(&binder)
@@ -1819,18 +1810,20 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         ExpnId::root(),
                         span.with_parent(None),
                     );
-                    let p_name = ParamName::Fresh(p_def_id);
-                    captures.insert(p_def_id, (span, p_id, p_name, res));
-                    hir::LifetimeName::Param(p_name)
+                    captures.insert(p_def_id, (span, p_id, ParamName::Fresh, res));
+                    hir::LifetimeName::Param(p_def_id, ParamName::Fresh)
+                } else if elided {
+                    hir::LifetimeName::Implicit
                 } else {
-                    l_name
+                    hir::LifetimeName::Underscore
                 }
             }
             LifetimeRes::Static => hir::LifetimeName::Static,
             LifetimeRes::Error => hir::LifetimeName::Error,
             res => panic!("Unexpected lifetime resolution {:?} for {:?} at {:?}", res, ident, span),
         };
         debug!(?self.captured_lifetimes);
+        debug!(?name);
         hir::Lifetime { hir_id: self.lower_node_id(id), span: self.lower_span(span), name }
     }
 

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -567,14 +567,14 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
         let lifetime =
             self.try_match_adt_and_generic_args(substs, needle_fr, args, search_stack)?;
         match lifetime.name {
-            hir::LifetimeName::Param(hir::ParamName::Plain(_) | hir::ParamName::Error)
+            hir::LifetimeName::Param(_, hir::ParamName::Plain(_) | hir::ParamName::Error)
             | hir::LifetimeName::Error
             | hir::LifetimeName::Static => {
                 let lifetime_span = lifetime.span;
                 Some(RegionNameHighlight::MatchedAdtAndSegment(lifetime_span))
             }
 
-            hir::LifetimeName::Param(hir::ParamName::Fresh(_))
+            hir::LifetimeName::Param(_, hir::ParamName::Fresh)
             | hir::LifetimeName::ImplicitObjectLifetimeDefault
             | hir::LifetimeName::Implicit
             | hir::LifetimeName::Underscore => {

compiler/rustc_borrowck/src/universal_regions.rs

@@ -830,11 +830,11 @@ fn for_each_late_bound_region_defined_on<'tcx>(
     fn_def_id: DefId,
     mut f: impl FnMut(ty::Region<'tcx>),
 ) {
-    if let Some((owner, late_bounds)) = tcx.is_late_bound_map(fn_def_id.expect_local()) {
+    if let Some(late_bounds) = tcx.is_late_bound_map(fn_def_id.expect_local()) {
         for &region_def_id in late_bounds.iter() {
             let name = tcx.item_name(region_def_id.to_def_id());
             let liberated_region = tcx.mk_region(ty::ReFree(ty::FreeRegion {
-                scope: owner.to_def_id(),
+                scope: fn_def_id,
                 bound_region: ty::BoundRegionKind::BrNamed(region_def_id.to_def_id(), name),
             }));
             f(liberated_region);

compiler/rustc_hir/src/hir.rs

@@ -26,7 +26,7 @@ use rustc_target::spec::abi::Abi;
 use smallvec::SmallVec;
 use std::fmt;
 
-#[derive(Copy, Clone, Encodable, HashStable_Generic)]
+#[derive(Debug, Copy, Clone, Encodable, HashStable_Generic)]
 pub struct Lifetime {
     pub hir_id: HirId,
     pub span: Span,
@@ -60,7 +60,7 @@ pub enum ParamName {
     /// ```
     /// where `'f` is something like `Fresh(0)`. The indices are
     /// unique per impl, but not necessarily continuous.
-    Fresh(LocalDefId),
+    Fresh,
 
     /// Indicates an illegal name was given and an error has been
     /// reported (so we should squelch other derived errors). Occurs
@@ -72,9 +72,7 @@ impl ParamName {
     pub fn ident(&self) -> Ident {
         match *self {
             ParamName::Plain(ident) => ident,
-            ParamName::Fresh(_) | ParamName::Error => {
-                Ident::with_dummy_span(kw::UnderscoreLifetime)
-            }
+            ParamName::Fresh | ParamName::Error => Ident::with_dummy_span(kw::UnderscoreLifetime),
         }
     }
 
@@ -90,7 +88,7 @@ impl ParamName {
 #[derive(HashStable_Generic)]
 pub enum LifetimeName {
     /// User-given names or fresh (synthetic) names.
-    Param(ParamName),
+    Param(LocalDefId, ParamName),
 
     /// User wrote nothing (e.g., the lifetime in `&u32`).
     Implicit,
@@ -127,7 +125,7 @@ impl LifetimeName {
             | LifetimeName::Error => Ident::empty(),
             LifetimeName::Underscore => Ident::with_dummy_span(kw::UnderscoreLifetime),
             LifetimeName::Static => Ident::with_dummy_span(kw::StaticLifetime),
-            LifetimeName::Param(param_name) => param_name.ident(),
+            LifetimeName::Param(_, param_name) => param_name.ident(),
         }
     }
 
@@ -136,9 +134,9 @@ impl LifetimeName {
             LifetimeName::ImplicitObjectLifetimeDefault
             | LifetimeName::Implicit
             | LifetimeName::Underscore
-            | LifetimeName::Param(ParamName::Fresh(_))
+            | LifetimeName::Param(_, ParamName::Fresh)
             | LifetimeName::Error => true,
-            LifetimeName::Static | LifetimeName::Param(_) => false,
+            LifetimeName::Static | LifetimeName::Param(..) => false,
         }
     }
 
@@ -148,12 +146,12 @@ impl LifetimeName {
             | LifetimeName::Implicit
             | LifetimeName::Underscore => true,
 
-            // It might seem surprising that `Fresh(_)` counts as
+            // It might seem surprising that `Fresh` counts as
             // *not* elided -- but this is because, as far as the code
-            // in the compiler is concerned -- `Fresh(_)` variants act
+            // in the compiler is concerned -- `Fresh` variants act
             // equivalently to "some fresh name". They correspond to
             // early-bound regions on an impl, in other words.
-            LifetimeName::Error | LifetimeName::Param(_) | LifetimeName::Static => false,
+            LifetimeName::Error | LifetimeName::Param(..) | LifetimeName::Static => false,
         }
     }
 
@@ -163,8 +161,8 @@ impl LifetimeName {
 
     pub fn normalize_to_macros_2_0(&self) -> LifetimeName {
         match *self {
-            LifetimeName::Param(param_name) => {
-                LifetimeName::Param(param_name.normalize_to_macros_2_0())
+            LifetimeName::Param(def_id, param_name) => {
+                LifetimeName::Param(def_id, param_name.normalize_to_macros_2_0())
             }
             lifetime_name => lifetime_name,
         }
@@ -177,12 +175,6 @@ impl fmt::Display for Lifetime {
     }
 }
 
-impl fmt::Debug for Lifetime {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "lifetime({}: {})", self.hir_id, self.name.ident())
-    }
-}
-
 impl Lifetime {
     pub fn is_elided(&self) -> bool {
         self.name.is_elided()
@@ -628,6 +620,16 @@ impl<'hir> Generics<'hir> {
         })
     }
 
+    pub fn outlives_for_param(
+        &self,
+        param_def_id: LocalDefId,
+    ) -> impl Iterator<Item = &WhereRegionPredicate<'_>> {
+        self.predicates.iter().filter_map(move |pred| match pred {
+            WherePredicate::RegionPredicate(rp) if rp.is_param_bound(param_def_id) => Some(rp),
+            _ => None,
+        })
+    }
+
     pub fn bounds_span_for_suggestions(&self, param_def_id: LocalDefId) -> Option<Span> {
         self.bounds_for_param(param_def_id).flat_map(|bp| bp.bounds.iter().rev()).find_map(
             |bound| {
@@ -769,6 +771,16 @@ pub struct WhereRegionPredicate<'hir> {
     pub bounds: GenericBounds<'hir>,
 }
 
+impl<'hir> WhereRegionPredicate<'hir> {
+    /// Returns `true` if `param_def_id` matches the `lifetime` of this predicate.
+    pub fn is_param_bound(&self, param_def_id: LocalDefId) -> bool {
+        match self.lifetime.name {
+            LifetimeName::Param(id, _) => id == param_def_id,
+            _ => false,
+        }
+    }
+}
+
 /// An equality predicate (e.g., `T = int`); currently unsupported.
 #[derive(Debug, HashStable_Generic)]
 pub struct WhereEqPredicate<'hir> {

compiler/rustc_hir/src/intravisit.rs

@@ -510,11 +510,11 @@ pub fn walk_label<'v, V: Visitor<'v>>(visitor: &mut V, label: &'v Label) {
 pub fn walk_lifetime<'v, V: Visitor<'v>>(visitor: &mut V, lifetime: &'v Lifetime) {
     visitor.visit_id(lifetime.hir_id);
     match lifetime.name {
-        LifetimeName::Param(ParamName::Plain(ident)) => {
+        LifetimeName::Param(_, ParamName::Plain(ident)) => {
             visitor.visit_ident(ident);
         }
-        LifetimeName::Param(ParamName::Fresh(_))
-        | LifetimeName::Param(ParamName::Error)
+        LifetimeName::Param(_, ParamName::Fresh)
+        | LifetimeName::Param(_, ParamName::Error)
         | LifetimeName::Static
         | LifetimeName::Error
         | LifetimeName::Implicit
@@ -879,7 +879,7 @@ pub fn walk_generic_param<'v, V: Visitor<'v>>(visitor: &mut V, param: &'v Generi
     visitor.visit_id(param.hir_id);
     match param.name {
         ParamName::Plain(ident) => visitor.visit_ident(ident),
-        ParamName::Error | ParamName::Fresh(_) => {}
+        ParamName::Error | ParamName::Fresh => {}
     }
     match param.kind {
         GenericParamKind::Lifetime { .. } => {}

compiler/rustc_middle/src/hir/map/mod.rs

@@ -364,7 +364,11 @@ impl<'hir> Map<'hir> {
         match node.node {
             OwnerNode::ImplItem(impl_item) => Some(&impl_item.generics),
             OwnerNode::TraitItem(trait_item) => Some(&trait_item.generics),
-            OwnerNode::Item(Item {
+            OwnerNode::ForeignItem(ForeignItem {
+                kind: ForeignItemKind::Fn(_, _, generics),
+                ..
+            })
+            | OwnerNode::Item(Item {
                 kind:
                     ItemKind::Fn(_, generics, _)
                     | ItemKind::TyAlias(_, generics)

compiler/rustc_middle/src/middle/resolve_lifetime.rs

@@ -6,7 +6,6 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::ItemLocalId;
 use rustc_macros::HashStable;
-use rustc_span::symbol::Symbol;
 
 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, HashStable)]
 pub enum Region {
@@ -22,12 +21,12 @@ pub enum Region {
 /// so that we can e.g. suggest elided-lifetimes-in-paths of the form <'_, '_> e.g.
 #[derive(Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, HashStable)]
 pub enum LifetimeScopeForPath {
-    // Contains all lifetime names that are in scope and could possibly be used in generics
-    // arguments of path.
-    NonElided(Vec<Symbol>),
+    /// Contains all lifetime names that are in scope and could possibly be used in generics
+    /// arguments of path.
+    NonElided(Vec<LocalDefId>),
 
-    // Information that allows us to suggest args of the form `<'_>` in case
-    // no generic arguments were provided for a path.
+    /// Information that allows us to suggest args of the form `<'_>` in case
+    /// no generic arguments were provided for a path.
     Elided,
 }
 

compiler/rustc_middle/src/query/mod.rs

@@ -1584,7 +1584,7 @@ rustc_queries! {
         Option<&'tcx FxHashMap<ItemLocalId, Region>> {
         desc { "looking up a named region" }
     }
-    query is_late_bound_map(_: LocalDefId) -> Option<(LocalDefId, &'tcx FxHashSet<LocalDefId>)> {
+    query is_late_bound_map(_: LocalDefId) -> Option<&'tcx FxHashSet<LocalDefId>> {
         desc { "testing if a region is late bound" }
     }
     /// For a given item (like a struct), gets the default lifetimes to be used

compiler/rustc_middle/src/ty/context.rs

@@ -2803,6 +2803,13 @@ impl<'tcx> TyCtxt<'tcx> {
         self.named_region_map(id.owner).and_then(|map| map.get(&id.local_id).cloned())
     }
 
+    pub fn is_late_bound(self, id: HirId) -> bool {
+        self.is_late_bound_map(id.owner).map_or(false, |set| {
+            let def_id = self.hir().local_def_id(id);
+            set.contains(&def_id)
+        })
+    }
+
     pub fn late_bound_vars(self, id: HirId) -> &'tcx List<ty::BoundVariableKind> {
         self.mk_bound_variable_kinds(
             self.late_bound_vars_map(id.owner)